1. Field of the Invention
The present invention relates to a power supply device such as a DC-DC converter connected to a DC power source, and to a method of determining abnormality in a power supply device.
2. Description of the Related Art
For example, a conventional power supply device includes the following configuration (see, for example, Japanese Patent Application Laid-open No. 2012-75207). A chopper switching element for chopping an output current of the DC power source and a flywheel semiconductor element are connected to the DC power source in series in this order. A reactor L and a load circuit are connected in series in this order to a node between the chopper switching element and the flywheel semiconductor element. The power supply device further includes a drive circuit for controlling ON/OFF of the chopper switching element, a charge circuit connected to the node between the chopper switching element and the flywheel semiconductor element, an output voltage detection circuit for detecting a voltage between the reactor and the load circuit, and an abnormality determination circuit for determining abnormality based on a detection result of the output voltage detection circuit.
The charge circuit is driven under the state where the chopper switching element is turned OFF. When an output voltage detection value of the output voltage detection circuit is equal to or lower than a predetermined value, the abnormality determination circuit determines a failure, and inhibits normal operation of the power supply device, that is, inhibits ON/OFF control of the chopper switching element, to thereby prevent the extension of damage to other components of the power supply device.
In the conventional power supply device described above, in the case where the load circuit includes a second DC power source, the output voltage detection value of the output voltage detection circuit corresponds to a voltage of the second DC power source. Thus, it has been difficult to determine the presence and absence of a failure of the power supply device based on the detection value.